SOM constructed from the Deep sample populated by redshift and objects number count. The SOM is constructed using 500 000 deep-sample objects with dimensions 75 × 150. Left: SOM populated with the 15 000 deep-sample objects that have z_obs information, where each cell shows the mean z_obs of the samples it contains. This shows the original Masters et al. (2015) method. Middle: SOM populated using the 500 000 MPT-Mock-sample objects, which are the wide-like counterparts of the deep-sample objects used to construct the SOM. Each cell shows the mean photo-z of the samples it contains (Scenario D, photo-z map). Right: SOM populated with the MPT-Mock-sample objects corresponding to the 15 000 deep-sample galaxies with z_obs information, each replicated through 50 independent realisations, in total 750 000 objects. The colour scale indicates the number of objects per cell (Scenario C, MPT-Mock sample occupation for the z_obs-sample projection). White colour indicates the empty cells. The middle and right plots reflect the MPT-Mock-sample object onto a deep-sample constructed SOM.